Yamahai is a great-sounding word, like something samurai warriors could yell when attacking. Yamahai is actually a natural, labor-intensive, somewhat risky style of sake production. Sakes made by the yamahai method can be intense and funky, both richer and more acidic than the great majority of sakes, which are made by more modern industrial methods. They're also likely to be more friendly to Western food - or richer Japanese food like pork-based dishes - than other sakes.
"I love the concept of yamahai because you're tasting the brewery itself," says Beau Timken, owner of True Sake, a store in San Francisco. "The yeasts that have been captured in the old wooden rafters of that building for hundreds of years - that's what you're tasting."
Relying on native yeasts carries risks, as winemakers know well, because there's no way to control what type of yeast is floating around in the air. You might get unique, earthy flavors, or you might get something that smells like a barnyard floor. To take that risk, a sake brewer has to either be an idealist, a seeker of differentiation from competitors, or both.
Very little sake is actually made by the yamahai method - less than 1 percent, says John Gauntner, a Japan-based American sake expert who advises the Japanese government on supporting sake exports. "It's a hassle to make," Gauntner says. "It takes longer, and you've got to make it in a separate room, isolated from all your other sakes. The majority of brewers make no yamahai."
Despite that, yamahai is disproportionately popular among American wine aficionados. Turn a wine geek conversation toward sake and the subject of yamahais inevitably follows.
"Lately we have many customers who ask for yamahai," says Yoshi Tome, owner of Sushi Ran in Sausalito. "They want richer sake. Sometimes they know wine better than sake, but they've had yamahai and they like it."
While most sake is compared to white wine, Tome believes yamahai is closer in body, flavor and complexity to red wine. "Yamahai is much more popular in the U.S. than in Japan," Tome says. "People who live in Japan get used to the Japanese taste - lighter flavors, a little sweetness. Subtle, delicate flavors. American restaurants serve food with very strong flavors. Even Japanese restaurants here serve food with stronger flavors. Yamahai is better with these foods."
Tome recommends them with nimono (meat, fish or vegetables boiled in soy sauce and dashi), some beef dishes and miso-marinated cod.
What exactly is yamahai? Ironically, for a method now seen as a return to the past, it was actually a labor-saving shortcut when originally developed about a century ago. But yamahai has never been the dominant method of production, because less than five years after it was developed, sake brewers invented the industrial "sokujo" method responsible for the overwhelming majority of sake today.
Sake is made from rice, water and koji mold - but in the same sense that wine is made from grapes. Those are the crucial main ingredients, but just as with wine, other things may be added during fermentation to help it along. One such item is lactic acid, found in dairy products. It helps prevent undesirable bacteria from creating unpleasant aromas and flavors and is largely responsible for the milky, creamy flavor of many sakes, though that's mostly a happy by-product of its germ-killing duties.
Brewers who didn't have access to a nice sterile, industrially produced bag of lactic acid - in other words, everyone until about 95 years ago - learned by trial and error to propagate bacteria that creates lactic acid. For about 300 years, until the early 20th century, this was done through the kimoto process, an exhausting, labor-intensive method that required brewers to stand over a starter mash of sake yeast and grind it into a paste with long, flat-headed poles.
Yamahai production dispenses with the poles. Instead, brewers carefully add the right microbes at the right time to build up lactic acid slowly and keep fermentation fizzing merrily along. Most breweries rely on native yeasts in the air, which means your sake might have been fermented by the descendants of yeasts that originally populated the brewery decades or even centuries before. But you don't smell yeast in yamahai - you smell lactic acid.
"When you smell a vat of yamahai, you smell a dairy product," Timken says. "It smells almost like yogurt."